2000 Suburban 5.3 Engine Knocking

[Tynan918]

Considering buying this 2000 Suburban to use as a reliable daily driver for my family of 7. This is the only full sized vehicle with 3rd row seating in my area that I can afford...seller is asking $1500. Clean inside and out.

Before contacting the seller, the sale description indicated the truck wasn't running because of water pump failure. Said the transmission was rebuilt and motor swapped by the previous owner. Has had some new parts installed.

After contacting the seller, I was sent a video of the motor running. The seller said they think the engine has a knock, but the sound didn't sound like a knock, it sounds as if something is just loose.

Here is the video they sent me..

Got the price dropped to $1,000 saving me some money for self repair and parts. I'll drive it to my grandparents 15 miles away, buy a hoist and get to turning wrenches.

If I have to remove and replace the motor, I have a 5.3 to rebuild, carburate, and throw into my GBody MC SS.

Anywho...

I just don't understand how a running vehicle parked for some small time because of a bad water pump can somehow develop an engine knock...

I need to figure out what the noise is and the route I'm going to have to take to get this truck reliably on the road again.

If I have a knock or broken internal parts and have to replace the engine as a whole, that's fine, I just need told how to R&R with this vehicle, and any reprogramming.

I also see a failed/failing knock sensor can cause an engine knock...how can I troubleshoot that to know if it's a faulty knock sensor or the knock is internal parts causing the knock ?

 

[Doubeleive]

Considering buying this 2000 Suburban to use as a reliable daily driver for my family of 7. This is the only full sized vehicle with 3rd row seating in my area that I can afford...seller is asking $1500. Clean inside and out.

Before contacting the seller, the sale description indicated the truck wasn't running because of water pump failure. Said the transmission was rebuilt and motor swapped by the previous owner. Has had some new parts installed.

After contacting the seller, I was sent a video of the motor running. The seller said they think the engine has a knock, but the sound didn't sound like a knock, it sounds as if something is just loose.

Here is the video they sent me..

Got the price dropped to $1,000 saving me some money for self repair and parts. I'll drive it to my grandparents 15 miles away, buy a hoist and get to turning wrenches.

If I have to remove and replace the motor, I have a 5.3 to rebuild, carburate, and throw into my GBody MC SS.

Anywho...

I just don't understand how a running vehicle parked for some small time because of a bad water pump can somehow develop an engine knock...

I need to figure out what the noise is and the route I'm going to have to take to get this truck reliably on the road again.

If I have a knock or broken internal parts and have to replace the engine as a whole, that's fine, I just need told how to R&R with this vehicle, and any reprogramming.

I also see a failed/failing knock sensor can cause an engine knock...how can I troubleshoot that to know if it's a faulty knock sensor or the knock is internal parts causing the knock ?

first thing you want to do is remove the belt's yes plural both serpentine and ac pump. then start it up briefly and see if the noise is gone.
that will tell you pretty much everything you need to know at this point.

 

[Tynan918]

first thing you want to do is remove the belt's yes plural both serpentine and ac pump. then start it up briefly and see if the noise is gone.
that will tell you pretty much everything you need to know at this point.

I'd hate to do that before buying, he realizes it ain't an engine knock, and he raises the price back up from our $1k deal.

I'm thinking and hoping this isn't an engine knock, but something else producing the sound of a knock.

1. Piston slap - GM says this is "normal" for these engines and there's nothing to do about it.

2. Stuck lifter/pushrod

3. Clogged Catalytic Converter

4. Loose/Failed Pulleys

5. Loose Torque Converter Bolts

6. Failing or Failed Knock Sensors

 

[Donal]

Buy it, fix it, enjoy it.

 

[RST Dana]

If it’s going to need expensive repairs, then $500 could but a place ticket to your next future purchase and then drive it home, but you’re probably going to pay more than $1,500. Take the belts off for piece of mind, or take a chance that the noise is from his washing machine, or keep shopping.

 

[strutaeng]

You'll have wait to diagnose it once you buy it...you obviously can't do that just by listening to a few seconds of video of it. It could be a lot of things. Buy yourself a cheap HF stethoscope to pinpoint the noise.

But yes, try to negotiate the price down in case worse case scenario and you need another engine.

 

[Doubeleive]

I'd hate to do that before buying, he realizes it ain't an engine knock, and he raises the price back up from our $1k deal.

I'm thinking and hoping this isn't an engine knock, but something else producing the sound of a knock.

1. Piston slap - GM says this is "normal" for these engines and there's nothing to do about it.

2. Stuck lifter/pushrod

3. Clogged Catalytic Converter

4. Loose/Failed Pulleys

5. Loose Torque Converter Bolts

6. Failing or Failed Knock Sensors

you said they told you it was water pump failure, taking the belt off confirms that, there should be no increasing the price. if anything it's not firing up at this point so it's not looking very hopefull

 

[Joseph Garcia]

I would be wondering how long the truck was driven with a failed water pump.

 

[Tynan918]

you said they told you it was water pump failure, taking the belt off confirms that, there should be no increasing the price. if anything it's not firing up at this point so it's not looking very hopefull

I would be wondering how long the truck was driven with a failed water pump.

I'm not too confident he knows the water pump failed...said he didn't even think of checking the thermostat.

He's letting me go check things out the coming up Sunday.

I'm going to put it on my scanner for codes, start it and let it run for a couple of minutes and check the oil pressure and listen to the motor with my stethoscope, drain the oil, knock on the cat converter for loose internals, and pull the belts and run the motor so I can see how it sounds without the pulleys turn.

 

[Tynan918]

you said they told you it was water pump failure, taking the belt off confirms that, there should be no increasing the price. if anything it's not firing up at this point so it's not looking very hopefull

I would be wondering how long the truck was driven with a failed water pump.